Opposition Leader Tony Abbott is reportedly considering building up to 100 dams across the country as part of a plan to prevent floods, fuel power stations and irrigate food bowls.

News Limited on Thursday reported that the leaked draft policy discussion paper included a $500 million plan to raise Warragamba Dam in Sydney.

The total cost of the water management plan, if all projects were approved, would be $30 billion.

In a foreword to the document, shadow finance minister Andrew Robb reportedly wrote: "A coalition government will not support the construction of dams for the simple sake of building dams, however, it will back projects that bring demonstrable community benefits.

"Many opportunities to pursue projects that would enhance water security, help to mitigate floods, provide hydro power, and perhaps most importantly to grow our economic prosperity while being sensitive to the environment, have been missed."